A method for image forming apparatuses to detect a charge voltage applied to a charger using a voltage dividing resistor is known. Furthermore, there is an art to detect the charge voltage using an auxiliary winding that is provided at the primary winding side of the transformer used for generating the charge voltage.
However, the configuration to detect the charge voltage using the auxiliary winding of the transformer is likely to cause a detection error more than the configuration to operate the detection using the voltage dividing resistor does. On the other hand, the method of operating the detection using the voltage dividing resistor undesirably causes a power loss due to the voltage dividing resistor.
Therefore, there is a need for an image forming apparatus and a charge-voltage generating method that can provide higher accuracy with less power loss in detection of the charge voltage.